Advances in 3D printing scaffolds for peripheral nerve and spinal cord injury repair

Because of the complex nerve anatomy and limited regeneration ability of natural tissue, the current treatment effect for long-distance peripheral nerve regeneration and spinal cord injury (SCI) repair is not satisfactory. As an alternative method, tissue engineering is a promising method to regenerate peripheral nerve and spinal cord, and can provide structures and functions similar to natural tissues through scaffold materials and seed cells. Recently, the rapid development of 3D printing technology enables researchers to create novel 3D constructs with sophisticated structures and diverse functions to achieve high bionics of structures and functions. In this review, we first outlined the anatomy of peripheral nerve and spinal cord, as well as the current treatment strategies for the peripheral nerve injury and SCI in clinical. After that, the design considerations of peripheral nerve and spinal cord tissue engineering were discussed, and various 3D printing technologies applicable to neural tissue engineering were elaborated, including inkjet, extrusion-based, stereolithography, projection-based, and emerging printing technologies. Finally, we focused on the application of 3D printing technology in peripheral nerve regeneration and spinal cord repair, as well as the challenges and prospects in this research field.